CN102245885A

CN102245885A - Control and regulation method for an internal combustion engine having a common rail system

Info

Publication number: CN102245885A
Application number: CN2009801480291A
Authority: CN
Inventors: A·德尔克
Original assignee: MTU Motoren und Turbinen Union Muenchen GmbH
Current assignee: Rolls Royce Solutions Ltd.
Priority date: 2008-11-24
Filing date: 2009-11-09
Publication date: 2011-11-16
Anticipated expiration: 2029-11-09
Also published as: US20110231080A1; EP2358987A1; DE102008058721B4; DE102008058721A1; WO2010057587A1; US9133786B2; CN102245885B; EP2358987B1

Abstract

The invention relates to a control and regulation method for an internal combustion engine (1) having a common rail system wherein the rail pressure (pCR) is regulated in normal operation in that an offset of the rail pressure (pCR) is calculated and a PWM signal (PWM) is determined for activating the control process via a pressure controller based on the offset, wherein a load rejection when the rail pressure (pCR) exceeds a limit and wherein upon recognition of the load rejection, the rail pressure (pCR) is controlled in that the PWM signal (PWM) is temporarily set to a PWM value that is higher compared to normal operation via a PWM parameter. The invention is characterized in that the threshold for activation of the temporary PWM parameter is calculated in dependence on the gradient of a power-determining signal.

Description

Be used to have the control and the regulating method of the internal-combustion engine of common rail system

Technical field

The present invention relates to be used to have the control and the regulating method of the internal-combustion engine of common rail system, therein, adjustable track pressure in normal running, and utilize the identification of unloading to be transformed into control operation from regulating operation, wherein in control operation, the pwm signal that will be used to act on controlled plant (Regelstrecke) is set to the PWM value that has improved with respect to normal running provisionally.

Background technique

In common rail system, high-pressure service pump is transported to fuel the track from fuel tank.The entrance cross-section that leads to high-pressure service pump is determined by variable suction throttle valve.The place is connected with sparger at track, and fuel is injected in the firing chamber of internal-combustion engine by sparger.Because the quality of burning depends on the stress level in the track fatefully, so regulate this stress level.The high-pressure regulation loop comprises pressure regulator, has the suction throttle valve of high-pressure service pump and as the track of controlled plant and the filter in feedback branch.In the high-pressure regulation loop, the stress level in the track is corresponding to regulated quantity.The measured force value of track is transformed to actual rail pressure by filter, and compares with theoretical rail pressure.The adjusting deviation that draws thus is transformed to the adjustment signal that is used for suction throttle valve by pressure regulator then.Adjust signal for example corresponding to have the unit liter/minute volume flowrate.Adjust signal and on electric, be implemented as the pwm signal that has constant frequency (for example 50Hz).Described before high-pressure regulation loop is known from file DE 103 30 466B3.

Because high dynamic, being discharged on the regulation technology is unmanageable process, and this is because after unloading, and rail pressure can rise with the pressure gradient up to 4000 crust/seconds.By passive pressure-limit valve (its 1950 the crust rail pressure the time open) protection common rail system avoid unallowed high rail pressure.If for example internal-combustion engine operation and realized completely unloading under the constant rail pressures of 1800 crust stably, the time period until the response of pressure-limit valve is 37.5ms so.

For the reliability of the adjusting that improves pressure, file DE 10 2,005 029 138B3 propose, and are transformed into control operation from regulating to operate after the identification of unloading.In control operation, the pwm signal that is used to control suction throttle valve is set to the PWM value that has improved by step function provisionally, and the pass closed procedure of suction throttle valve quickens thus, and fuel seldom is transported in the track.After through the step function that is subjected to time control, and then turn back in the adjusting operation.Unloading is identification thus, and promptly actual track pressure surpasses fixing limit value.Shown method proves feasible when complete discharge (being that generator loading is reduced to 0% from 100%).

Yet determine that in practice this method also is not optimum when part unloads.If only other electric consumption device is not worked, there is the part unloading so.In disadvantageous situation, pressure surge appears in track, and this is caused thus, promptly utilizes default repeatedly the operation from adjusting in succession of interim PWM to be transformed into the control operation.

Summary of the invention

Default based on the interim PWM described in file DE 10 2,005 029 138B3, the objective of the invention is to, when part unloads, optimize pressure and regulate.

This purpose realizes by the feature of being implemented in claim 1.Design proposal is shown in the dependent claims.

This optimization is, is used to activate the gradient that the default limit value of interim PWM depends on the signal of determining power and calculates.At this, the signal of determining power is corresponding to theoretical rotational speed, ideal torque or theoretical emitted dose.Theoretical rotational speed also can be corresponding to accelerator pedal position.As the metering of amount, for example use the gradient of ideal torque to unloading.The piece more that this value descends, it is many more that load reduces ground.The present invention promptly at first realize the decline of the signal of definite power when unloading, and rail pressure raises on time lag ground just promptly based on following understanding.Limit value determines that by the self characteristics curve it is implemented with following form, promptly adjusts lower limit value when complete discharge, and adjust higher limit value in contrast when part unloads.

The method according to this invention is set to replenishing method known from file DE 10 2,005 029 138B3.Advantageously, the reason of having got rid of the fluctuation of the rail pressure when part unloads.Therefore, rail pressure illustrates more uniform change curve.Not only when complete discharge, and when part unloads, stop opening unintentionally of passive excess pressure valve under the situation of stable at the same time rail pressure.As the pure software solution, the sensor that meaning is promptly additional or optional in the change at electronic type motor controller place, conversion of the present invention almost is that expense is moderate.

Description of drawings

Preferred embodiment shown in the drawings.Wherein:

Fig. 1 illustrates system diagram,

Fig. 2 illustrates the high-pressure regulation loop as skeleton diagram,

Fig. 3 illustrates the skeleton diagram that is used to determine to control signal,

Fig. 4 illustrates the characteristic curve that is used for determining limit value,

Fig. 5 illustrates the unloading as time chart, and

Fig. 6 illustrates program flow diagram.

Embodiment

Fig. 1 illustrates the system diagram of the electronically controlled internal-combustion engine 1 that has common rail system.Internal-combustion engine 1 drives unshowned emergent motor (Notstromaggregat).Common rail system comprises the low pressure pump that is used for carrying the fuel that comes from fuel tank 23 as mechanical component, the suction throttle valve 4 that is used to influence volume flowrate, high pressure oil pump 5, track 4 and is used to inject fuel into the sparger 8 of the firing chamber of internal-combustion engine 1.

Internal-combustion engine 1 is controlled by electronic type motor controller 9 (ECU).Rail pressure pCR (it is surveyed by pressure transducer 7), the motor rotary speed nMOT of the input quantity as electronic type motor controller 9 shown in Figure 1 and amount EIN.The other input signal of amount EIN representative is for example represented oily temperature or fuel temperature.The shown output quantity of electronic type motor controller 9 is the pwm signal PMW that is used to control suction throttle valve 4, be used to control signal INJ and amount AUS that the sign of sparger 8 is sprayed.On behalf of injection beginning, injection cycle and injection, characterize the signal INJ that sprays finish.Amount AUS representative is used for the other regulated signal of controlling combustion engine 1, for example is used to control the adjustment signal of AGR valve.Shown common rail system also is embodied as the common rail system that has single memory certainly.In this case, single memory is integrated in the sparger 8, and wherein, single memory pressure p E is another input signal of electronic type motor controller 9 so.

Fig. 2 illustrates the high-pressure regulation loop that is used for adjustable track pressure as skeleton diagram.The input quantity of regulating loop is theoretical rail pressure pCR (SL).Output quantity is corresponding to the original value of rail pressure pCR.By the original value of rail pressure pCR, determine the first actual track pressure p CR1 (IST) by first filter 15.It is compared with theoretical rail pressure pCR (SL) at summing junction A place, produces thus to regulate deviation ep.Pressure regulator 10 calculates adjustment amount by regulating deviation ep.Adjustment amount is corresponding to volume flowrate qV1, and its physics unit is liter/minute.Optimally be arranged to, calculate theory consumption be added to volume flowrate qV1.Volume flowrate qV1 limits by limitation part 11 then.Limitation part 11 is embodied as and depends on rotating speed, input quantity nMOT.The output quantity of limitation part 11 is volume flowrate qV2.If the value of volume flowrate qV1 is arranged in the scope of permission, then the value of volume flowrate qV2 equals the value of volume flowrate qV1.By calculating part 12, volume flowrate qV2 is converted into pwm signal PWM1.Pwm signal PWM1 is in the on-time this illustrate, and frequency f PWM is corresponding to the frequency of for example 50Hz.When converting, consider the fluctuation of operating voltage and fuel precompressed simultaneously.Pwm signal PWM1 is first input quantity of switch 13.Second input quantity of switch 13 is pwm signal PWM2.Switch 13 is controlled by means of adjusting signal SZ by function block 17.The output signal PWM of switch 13 according to the position of switch 13 corresponding to signal PWM1 or signal PWM2.Then, utilize the field coil of pwm signal PWM effect suction throttle valve.Thus, change the stroke of magnetic core, freely influence high-pressure service pump ground feed flow thus.High-pressure service pump, suction throttle valve and track are corresponding to controlled plant 14.From track, draw consumption volume flowrate qV3 by sparger.So regulating loop closure.

This regulating loop replenishes by interim PWM is default, and it comprises the function block 17 that is used to calculate second filter 16 of the second actual track pressure p CR2 (IST) and is used for determining to adjust signal SZ.Second filter 16 has than the littler basically time constant of first filter 15.Function block 17 is shown in Figure 3, and makes an explanation with Fig. 3 with interrelating.The input quantity of function block 17 is ideal torque MSL, theoretical emitted dose QSL and theoretical rotational speed nSL.Thus, determine that the signal of power is corresponding to ideal torque MSL or theoretical emitted dose QSL or theoretical rotational speed nSL.Replace theoretical rotational speed nSL, also can use accelerator pedal position.In regulating operation, switch 13 is arranged in position a.In a of position, the pwm signal that is used to act on controlled plant 14 is determined by pressure regulator 10.If the second actual track pressure p CR2 (IST) surpasses limit value, function block 17 changes the signal level of adjusting signal SZ so, and switch 13 redirect among the b of position thus.In the b of position, export the PWM value PWM2 that improves with respect to normal running provisionally by PWM default 18.In other words: be transformed into control operation from regulating operation.Interim PWM is default, and to be embodied as (going out as shown) stepped, and it has respectively for example first and second time lags (Zeitstufe) of 10ms.After this time period of process, switch 13 conversion is then got back among a of position.Therefore, be arranged to regulate operation once more.

Fig. 3 illustrates the function block 17 that is used for determining to adjust signal SZ, utilizes and adjusts the position that signal SZ determines switch 13.Input quantity is ideal torque MSL, theoretical emitted dose QSL and theoretical rotational speed nSL.Output quantity is for adjusting signal SZ.Determine that by signal S1 in three input signals which is used for determining limit value (selection portion 19).Similarly, determine that in three characteristic curves 21 which is activated by signal S1.Description in addition for example realizes by means of ideal torque MSL.Determine the gradient G RAD of ideal torque MSL by calculating part 20, and pass through characteristic curve 21, the related gradient G RAD of limit value GW.Characteristic curve 21 is shown in Figure 4, and makes an explanation with interrelating with it.By comparator 25, the limit value GW and the second actual track pressure p CR2 (IST) compare each other.If the second rail pressure pCR2 (IST) surpasses limit value GW, be provided with so and adjust signal SZ, switch 13 is transformed among the b of position thus.In the b of position, interim PWM is default, i.e. control operation is activated.

In three characteristic curves 21 shown in Figure 4 one is the ideal torque as input quantity here.On abscissa, describe gradient G RAD (Nm/s of unit).On y coordinate, describe limit value GW (unit crust).Characteristic curve 21 is by first straight segments 22 that is parallel to abscissa, and second straight segments 23 with positive slope is formed with the 3rd straight segments 24 that is parallel to abscissa.Of the present inventionly be contemplated that substantially, by characteristic curve 21 limiting design value GW changeably.If reduce high load in when unloading, produce so ideal torque MSL very high negative gradient GRAD (GRAD＜-60000Nm/s).Therefore calculate limit value GW by first straight segments 22, it only is on the stable rail pressure of 1800 maximums of clinging to slightly, is here: 1840 crust.Avoid activating too late interim PWM thus and improve, and passive pressure-limit valve responds when the rail pressure of 1950 crust.If it is little of medium load to descend in when unloading in contrast, produce so ideal torque MSL little negative gradient GRAD (0＞GRAD＞-25000Nm/s).Therefore, calculate the limit value that GW=1970 clings to by the 3rd straight segments 24, the activation that makes interim PWM improve keeps under the situation that does not have effect.The medium load if descend, produce so medium gradient G RAD (60000＜GRAD＜-25000Nm/s), by related this gradient of the limit value of second straight segments, 23 correspondences.For example, gradient G RAD=-43000Nm/s divides the limit value of sending out the GW=1900 crust by the operating point A on second straight segments 23.

Fig. 5 illustrates the unloading as time chart.Fig. 5 is made up of subgraph 5A to 5C.Fig. 5 A illustrates the change curve of ideal torque MSL about the time.Fig. 5 B illustrates as the theoretical rail pressure pCR (SL) of dotted line about the change curve of time and rail pressure pCR (original value) change curve about the time.Fig. 5 C illustrates the change curve of pwm signal PWM about the time.In Fig. 5 B and Fig. 5 C, solid line is represented the change curve according to prior art, and in contrast, dotted line is represented according to change curve of the present invention.Load to the basis of the unloading of 50% load from 100% as other observation.

Flow process according to the method for prior art is as follows:

Ideal torque MSL is reduced to 5000Nm from 10000Nm behind time point t1.Because theoretical rail pressure pCR (SL) depends on ideal torque MSL by the characteristic field and theoretical rotational speed calculates, so theoretical rail pressure pCR (SL) is reduced to 1750 crust (Fig. 5 B) from 1800 crust behind time point t1.After unloading, rail pressure pCR raises.(Fig. 2: ep), pressure regulator calculates the pwm signal that increases among the time range t1/t2 in Fig. 5 C according to the negative adjusting deviation that increases.On closing direction, handle suction throttle valve by the pwm signal PWM that increases.To time point t2, rail pressure pCR surpasses fixing limit value GW=1840 crust, thus, is transformed into control operation from regulating operation.By pwm signal is at first brought up to 100% and during the process of two time lags, in control operation, activate interim PWM and improve then to the method for on-time of 50%.As the result that interim PWM improves, rail pressure pCR descends once more, and (und zwar) is up to about 1650 crust.Therefore, regulating deviation raises up to about 100 crust.If rail pressure pCR drops under the theoretical rail pressure pCR (SL), finish the time lag that so interim PWM improves, and makes that regulating operation activates once more.As the result who just regulates deviation who produces, the PWM on-time drops to 4% minimum value behind time point t3.Suction throttle valve is fully opened now once more, makes rail pressure pCR raise significantly.Because 50 crust below the theoretical rail pressure when theoretical rail pressure pCR (SL) only is in 100% load when 50% load are so rail pressure pCR (time period t 4/t5) when overshoot reaches the limit value GW of 1840 crust once more.Therefore, be transformed in the control operation again and activate interim PWM and improve to time point t5.As a result of, rail pressure pCR descends once more.As apparent by rail pressure pCR (solid line) institute from Fig. 5 B, the repeatedly activation that interim PWM improves causes the corresponding pressure surge of rail pressure pCR.

The flow process of the method according to this invention is as follows:

Change curve compute gradient GRAD by ideal torque MSL.In this example, by the limit value association of

characteristic curve

21,1900 crust calculate gradient G RAD.This limit value is marked as the line 26 that is parallel to time shaft at Fig. 5 B.Rail pressure pCR remains under this limit value, makes interim PWM improve and is not activated.Therefore, remain in the adjusting operation.According to the adjusting deviation that originally increases, send the PWM value of 22% maximum, this means that suction throttle valve is closed fully.As shown in Fig. 5 B, the current ripple disable of rail pressure pCR (dotted line) ground is near theoretical rail pressure pCR (SL).

Fig. 6 illustrate method minimizing program flow diagram.When this method begins, regulate actuator-activated.In S1, read in the theoretical rail pressure pCR (SL) and the first actual track pressure p CR1 (IST) and in S2, calculate adjusting deviation ep.According to regulating deviation ep, pressure regulator is determined its adjustment amount (it is converted into pwm signal PWM1), S3.Utilize this signal effect controlled plant then, this is because switch (Fig. 2: 13) be arranged in position a.Therefore PWM=PWM1 works S4.In S5, calculate the gradient G RAD of the signal of determining power.The signal of determining power is corresponding to ideal torque MSL, theoretical emitted dose QSL or theoretical rotational speed nSL.Ideal torque MSL and theoretical emitted dose QSL are corresponding to the adjustment amount of speed adjusting circuit.Then in S6, by selected characteristic curve (Fig. 4: 21) determine variable limit value GW.After this, in S7, inquire, the second actual track pressure p CR2 (IST) whether greater than/equal the second actual track pressure p CR2 (IST).If not this situation, inquire S7 as a result: not, in S9, regulate operation and keep activation and pwm signal as before corresponding to value PWM1.Program circuit finishes so.In contrast, if in S7, determine, the second actual track pressure p CR2 (IST) greater than/equal limit value, inquiry is S7 as a result: be, be transformed into control operation so and activate interim PWM raising in S8, during this period, pwm signal PWM is corresponding to signal PWM2.After this, program circuit finishes.

Reference identification

1 internal-combustion engine

2 fuel tanks

3 low pressure pumps

4 suction throttle valves

5 high-pressure service pumps

6 tracks

7 pressure transducers (track)

8 spargers

9 electronic type motor controllers (ECU)

10 pressure regulators

11 limitation part

12 pwm signal calculating parts

13 switches

14 controlled plants

15 first filters

16 second filters

17 function blocks

18 PWM are default

19 selection portions

20 calculating parts

21 characteristic curves

22 first straight segments

23 second straight segments

24 the 3rd straight segments

25 comparators

26 limit values

Claims

1. a control and regulating method that is used to have the internal-combustion engine (1) of common rail system, therein, by the adjusting deviation (ep) of calculating common rail pressure (pCR) and the method that is identified for controlling the pwm signal (PWM) of controlled plant (14) by means of described adjusting deviation (ep) by pressure regulator (10), in normal running, regulate described common rail pressure (pCR), if described therein common rail pressure (pCR) surpasses limit value (GW), then identify unloading, and therein by described pwm signal (PWM) is set to provisionally the method for the PWM value (PWM2) that improves with respect to normal running by PWM default (18), utilize the identification of unloading to control described common rail pressure (pCR), it is characterized in that, be used to activate the gradient (GRAD) that the described interim default described limit value (GW) of PWM depends on the signal of determining power and calculate.

2. method according to claim 1 is characterized in that, described limit value (GW) is determined by selectable characteristic curve (21).

3. method according to claim 2 is characterized in that, the signal of described definite power is corresponding to ideal torque (MSL), theoretical emitted dose (QSL) or theoretical rotational speed (nSL).

4. method according to claim 3 is characterized in that, described ideal torque (MSL) or described theoretical emitted dose (QSL) are determined as adjustment amount in speed adjusting circuit.

5. method according to claim 3 is characterized in that, described theoretical rotational speed (nSL) is corresponding to accelerator pedal position.